Magnetostrictive transducers are used extensively for industrial and medical applications as well as for underwater acoustics wherein the transducer often serves as both a sound source and receiver.
The transducers are fabricated utilizing a magnetostrictive material which changes its dimension when exposed to a magnetic field generated by supplying current to a coil of wire surrounding the material. Conversely, a change in length of the material, as may be caused by an impingement of an acoustic signal, will create a corresponding electric signal in the coil for detection purposes.
In order to achieve satisfactory magnetostrictive action, various candidate materials must undergo a multitude of manufacturing processes such as magnetic annealing, rolling, re-annealing, etc., in order to orient the magnetic domains of the material in a preferred direction. Other transducer materials require the constant application of a stress to achieve the preferred domain orientation and loss of the applied stress during use results in transducer inoperability.
The transducer of the present invention can operate using the above materials but can also be made to operate satisfactorily with non-oriented and unstressed materials. It can also be operated in such a manner as to fully utilize the magnetostrictive potential of any material.